January 25, 2022
The number of people with dementia is expected to nearly triple in the next three decades, according to a new analysis of global trends. Much of the rising caseload is a result of a growing and aging global population, according to the report. Cases will also continue to increase because of rising rates of obesity, diabetes and other risk factors for Alzheimer’s disease, the most common form of dementia.
Currently, more than 57 million people worldwide are living with Alzheimer’s disease or other forms of dementia. That number will increase to more than 83 million by 2030, 116 million by 2040, and 152 million by 2050, according to the new report. Today, more than 5 million men and women in the United States have Alzheimer’s disease or other forms of dementia, according to the report, with that total expected to double to more than double by 2050.
The findings, published in The Lancet Public Health, underscore the urgent need for more effective therapies for Alzheimer’s disease and other forms of dementia. Current therapies for Alzheimer’s may ease symptoms for a time but do nothing to stop the relentless progression of disease.
According to the new report, cases will rise worldwide, but in some areas of the world cases will rise faster than in others. The slowest rise in cases will be in Western Europe and high-income Asian countries like Japan, where population growth is slowing. The fastest rise in cases will be in Africa and the Middle East, a result of a growing population that will be aging in coming decades.
In the United States, cases of Alzheimer’s disease and other forms of dementia more than doubled in the past two decades, in part because of increased life expectancy and an aging population. Advanced age is a major risk factor for Alzheimer’s disease.
The caseload will continue to rise in the U.S. in coming decades, according to the report, but more slowly than in other areas of the world. Experts attribute slowing rates of dementia in the U.S. and other developed countries in part to improved management of heart disease and its risk factors. What’s good for the heart is good for the brain, studies show, and better control of high blood pressure, high cholesterol and other cardiovascular risk factors may help to protect brain health.
Slower rates of dementia may also be a result of growing levels of educational attainment, the study authors note. Having many years of schooling is associated with a lower risk of Alzheimer’s, in part because formal education is thought to build up a so-called cognitive reserve of rich connections in the brain that may “step in” if some brain cells are lost to the disease. In the same way, having a challenging job or completing cognitively stimulating activities like word games and crossword puzzles may also help build up cognitive reserve, studies suggest.
Worldwide, women will also continue to account for the majority of cases of dementia in coming decades. For every five cases in women, there will be three cases in men, the researchers estimate. The higher numbers are driven in part because women tend to live longer than men. There may also be sex-specific differences in the underlying causes of Alzheimer’s that make women more susceptible to the disease than men.
By 2050, according to the reports forecasts, dementia will affect 0.6 percent of women aged 40 to 69; 8.5 percent of women aged 70 to 84; and 30.5 percent of women 85 and older. Dementia will 0.5 percent of men aged 40 to 69; 6.5 percent of men aged 70 to 84; and 23.5 of men aged 85 and older.
The authors of the new report note that in order to stem the growth of dementia, it will be important to address potentially modifiable risk factors for Alzheimer’s and other forms of dementia. Researchers have identified 12 such modifiable risk factors: low levels of education, hypertension, hearing impairment, smoking, midlife obesity, depression, physical inactivity, diabetes, social isolation, excessive alcohol consumption, head injury, and air pollution.
Addressing these factors through public health interventions is a pathway towards reducing disease prevalence, they write, and future changes in modifiable risk factors might influence the trajectory of trends in age-specific prevalence. Up to 40 percent of dementia cases might be preventable through addressing such risk factors.
By ALZinfo.org, The Alzheimer’s Information Site. Reviewed by Marc Flajolet, Ph.D., Fisher Center for Alzheimer’s Research Foundation at The Rockefeller University.
Source: GBD 2019 Dementia Forecasting Collaborators: “Estimation of the global prevalence of dementia in 2019 and forecasted prevalence in 2050: an analysis for the Global Burden of Disease Study 2019.” The Lancet Public Health, January 6, 2022
